Protective coating



4 Patented Oct. 13, 1942 UNITED STATES PATENT; OFFICE PROTECTIVE coA'rl'Na Harry E. Rogers, Chicago, Ill., assignmto Tole-l type Corporation, Chicago, 11]., a corporation of Delaware No Drawing. Application October 13, 1939, Serial No. 299,273

1 Claim. (01. 117-134 The present invention relates to surface treating' compounds for metals and metallic alloys and particularly to processes of application therefor.

The principal object of this invention is to develop a process of treating metal surfaces to prevent corrosion by the application of thin coat- ,mgs of lanolin or similar slushing material under conditions of utmost sa ety from fire and explosion hazards.

Lanolin, a wax-like fat or grease which is obtained principally from sheep's or lambs wool, possesses the characteristics of tenacious adherence to metallic surfaces to such a degree that it has become recognized as "an excellent cor-- rosion inhibitor. In addition, it, almost exclusively among slushing compounds, is substantially free from any tendencies to form corrosive residue. In its natural state, however, this product is too thick, even when heated, to'be applied satisfactorily and efficiently to the surfaces of close-tolerance machine parts. As 'a resu1t,.the' thickness may protective film when of excess interfere with and even prevent close fitting piece parts from being assembled. Under such circumstances, it was found necessary to reinove the preferable because it is least corrosive and remains more nearly neutral following application 4 upon ferrous alloys. ducted to determine a proper quantity of lanolin may beheld in solution for the purpose of dip or immersion coating of machined parts. i

The use of trichloroethylene as a degreasing agent, both in vaporous as well as in liquid form,

A range of tests was conhad been known before, and while it appears that its use as an applicator solvent, in view of this practice, might be paradoxical, it was found, nevertheless, that by obtaining concentrated solutions of lanolin in trichloroethylene at temperatures ranging from 150 degrees F. to 190 degrees F., a suitable film thickness could be deposited both on ferrous as well as nonferroug 55 these two solvents, trichloroethylene is somewhat.

the temperature at which F through the vaporization zone. nt which has-proved more effective, however,

metallic alloys to enable them to withstand the ravages of ordinary corrosive atmospheres. Heavier coating films produced in this manner were found-to possess-sufiicient qualities of ad- 5 herence to withstand more extreme climatic conditions and exposures to humid atmospheres during all seasons of the year. thus applied though adhesive and elastic .so as to remain stable under temperature changes are, nevertheless, not greasy or oily to the touch even under extraordinary room temperature conditions, Foriordin'ary dipping operations, the concentration of lanolin is preferably maintained at about 12% to byweight and for producing heavy films, the concentration may be raised to about.40%. to

Surface deposits thus applied may be regulated as to thickness by varying the concentration of 0 the solution, and, by reducing the proportions of lanolin to about 5% by weight, the films may be produced so nearly transparent as not to require removal for the sake of appearance. The re- -moval of the film, if desired,* however, may be eilected in the conventional manner; that is, by V suspending in heated solvents or in the vapors thereof.

It is to be noted that rapid vaporization of trichloroethylene begins at degrees F. so that when dipping in the higher temperature solutions for the purpose of obtaining relatively thinner film deposits, care should be exercised to avoid'the formation of excessive vapor-zones above the dipping solution. Otherwise upon the removal of piece parts slowly, the degreasing action will be encountered by the wet piece parts upon passing through the vapor zone. 'Where the higher temperature of dipping solutions is so much preferred as to warrant the risk of generating rapid vaporization, a simple and for most purposes adequate precautionagainst degreasing' may be had by a quick withdrawal of the piece parts from the solution or vby a rapid passing Another expediunder these conditions of dipping consists in the provision of a condensation coil" disposed above and near the surface of the dipping solution and located perimetrically around the walls of the 50 solution container. I v While lanolin may be applied by the use of other volatile solvents, none has been found so well 'suited, noninfiammable, and at the same time possessing a vaporization point so much h gher than the belting point of lanolin. since The film deposits trichloroethylene has no iiash point, its use in buildings is safe and always permissible even an industrial plant may be governed by restrictions, Under where insurance underwriters various'ranges of the described formula, lanolin has been applied thoroughly to metal surfaces and even the thinnest application film following the volatilization of the' solvent was found to be entirely impervious to moisture and other corrosive atmospheres.

What is claimed is:

A process of coating metallic piece parts to prevent tarnish or oxidation which consists in and withdrawing the piece parts by moving them upwardly rapidlythrough the subdued evaporation zone overlying the solution.

HARRY E. ROGERS. 

